The present invention relates to microfluidic devices, and more particularly, to a method and apparatus for distributing fluid on a microfluidic device.
Methods of making a homologous series of compounds, or the testing of new potential drug compounds comprising a series of light compounds, has been a slow process because each member of a series or each potential drug must be made individually and tested individually. For example, a plurality of potential drug compounds is tested by an agent to test a plurality of materials that differ perhaps only by a single amino acid or nucleotide base, or a different sequence of amino acids or nucleotides.
The processes described above have been improved by microfluidic chips which are able to separate materials in a microchannel and move the materials through the microchannel is possible. Moving the materials through microchannels is possible by use of various electro-kinetic processes such as electrophoresis or electro-osmosis. Fluids may be propelled through various small channels by the electro-osmotic forces. An electro-osmotic force is built up in the channel via surface charge buildup by means of an external voltage that can repel fluidly and cause flow.
Another method for the movement of fluids is the use of an electrohydrodynamic pump. In electro-osmotic and electrohydrodynamic pumping, electrodes are placed within the microfluidic structure.
In fluid delivery in microfluidic structures, it is important to distribute approximately the same fluid volume to each reaction well. In using certain fluids, however, even distribution within reaction wells is difficult to accomplish.
It is, therefore, one object of the invention to provide an improved fluid delivery mechanism to an array of reaction wells. It is a further object of the invention to provide a reliable method for delivering fluid to reaction wells.
It is another object of the present invention to create a relatively small device which can carry out hundreds and even thousands of chemical experiments simultaneously, create new compounds, and measure their reactivities.
It is yet another object of the present invention to provide a liquid handling drug discovery and diagnostic tool which increases the speed and productivity of discovering new drug candidates and does so on a miniaturized, scale or platform that reduces cost and manual handling. It is still a further object of the present invention to provide a multiple fluid sample processor, system and method which is capable of conveying, transporting, and/or processing samples in a large multiplicity of sites without exposure to the atmosphere.
In one aspect of the invention, a microfluidic fluid delivery system includes a microfluidic device having a fluid input. A fluid reservoir is fluidically coupled to the fluid input. A gas delivery system has a pulse generator that generates an electric pulse. An electrically operated valve is coupled to the pulse generator and the gas pressure source. The valve controls the gas pressure pulse in response to said electric pulse. The gas pressure pulse displaces fluid from the fluid reservoir into the plurality of capillaries.
In a further aspect of the invention, a method of distributing fluid to a microfluidic chip comprises the steps of: providing a reservoir having fluid therein; pressurizing the fluid at a first pressure; filling the channel in the microfluidic device until the channel is filled to the capillary break; generating a pressure pulse; and thereby, displacing fluid from the reservoir in response to the pressure pulse.
One advantage of the invention is that small and controlled amounts of fluid may be delivered in an array structure with microchannels that have high pressure losses. Another advantage of the invention is that the method for delivering fluid to microfluidic structures is applicable to structures having high integration densities and where viscous losses in micro channels are significant.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.